You might install Postgis to implement very powerful spatial functionality that can easily do what you are asking (plus
awhole lot more).
http://www.postgis.org
Now that v2 installs as a Postgres extension, it is more closely coupled with the underlying database.
Brent Wood
Programme leader: Environmental Information Delivery
NIWA
DDI: +64 (4) 3860529
________________________________________
From: pgsql-general-owner@postgresql.org [pgsql-general-owner@postgresql.org] on behalf of Olivier Chaussavoine
[olivier.chaussavoine@gmail.com]
Sent: Saturday, August 10, 2013 7:29 AM
To: pgsql-general@postgresql.org
Subject: [GENERAL] earthdistance
I develope a project openbarter that needs to match objects based on a maximum distance between their positions on
earth.I saw that the documentation of the extension earthdistance was interesting, but the promise was not in the code.
Itwould be nice to have these functions available independently of sophisticated geographic systems. There is a circle
objectfor flat two dimensional space, but earth deals with spherical caps. It would not be exact but enough to suppose
thatearth is a sphere and that all dimensions latitude, longitude and distance are in radian.
What would need to be done to adapt the circle type to a new type 'spherical cap' that would allow simple geographic
indexing?
--
Olivier Chaussavoine
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